mk5087 ETC-unknow, mk5087 Datasheet - Page 5

• Manufacturer Part Number: mk5087
• Description: Dtmf Generator
• Manufacturer: ETC-unknow

MV5087
OUTPUT FREQUENCY
standard DTMF frequencies when a 3.58MHz crystal is used
as the reference.
synthesised using R-2R D-to-A converters (see Fig.6),
resulting in a ‘staircase’ approximation to a sinewave. An
opamp mixes these tones to produce a dual-tone waveform.
Single tone distortion is typically better than 7% and all
distortion components of the mixed dual-tone should be 30dB
relative to the strongest fundamental (column tone).
DISTORTION MEASUREMENTS
Where V2f --- Vnf are the Fourier components of the waveform.
THD for the dual tone is defined by:
4
Table 1 shows the output frequency deviation from the
The row and column output waveforms are digitally
THD for the single tone is defined by:
where
V
V
V
V
V
ROW
COL
2R
2C
IMD
—V
—V
is the sum of all intermodulation components.
is the column fundamental amplitude
is the row fundamental amplitude
nR
nC
a)
b)
are the Fourier component amplitudes of the row frequencies
are the Fourier component amplitudes of the column frequencies
V
V
OUT
OUT
Figure 6: Typical sinewave output (a) Row tones (b) Column tones
100 (
100 (
V
V
2
2R
2
2f
+ V
+ V
V
3R
2
3f
2
fundamental
+ V
+ V
Column
nR
2
V
Row
4f
2
+ V
ROW
2
+ ---- V
2C
2
+ V
+ V
f
f
f
f
f
f
f
f
1
2
3
4
5
6
7
8
Standard
nf
2
3C
2
DTMF
Table 1: Output frequency deviation
) %
(Hz)
COL
2
--- V
697
770
852
941
1209
1336
1477
1633
nc
2
+ V
Frequency Using
IMD
t
2
3.5795545 MHz
t
Tone Output
)
Crystal
701.3
771.4
857.2
935.1
1215.9
1331.7
1471.9
1645.0
from Standard
% Deviation
+0.62
+0.19
+0.61
-0.63
+0.57
-0.32
-0.35
+0.73
High
Group
Low
Group